Mars Reconnaissance Orbiter (MRO)
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Northern_Plains-Psp_001380_2520_red-01.jpgAnother "Frozen Lake" in the Northern Plains? (2 - EDM - False Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)55 visitenessun commentoMareKromium
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PIA08013_modest.jpgThe "First Frame" from MRO99 visiteThis view shows a full-resolution portion of the first image of Mars taken by the High Resolution Imaging Science Experiment camera (HiRISE) on NASA's Mars Reconnaissance Orbiter. The spacecraft, launched Aug. 12, 2005, began orbiting Mars on March 10, 2006. The image is of an area in Mars' mid-latitude Southern Highlands.
HiRISE took this first test image from orbit on March 24, 2006, from an altitude of 2.489 Km (about 1.547 miles), achieving a resolution of 2,49 mt (98" - inches) per pixel, or picture element. The smallest objects of discernable shape are about 3 pixels across. An image acquired at this latitude during the Mars Reconnaissance Orbiter's main science phase, beginning in fall 2006, would be taken from an altitude of about 280 Km (approx. 174 miles) and have a resolution of 28 cm (11") per pixel.
This view covers an area about 4,5 by 2,1 Km (about 1,6 by 1,3 miles).
The quality of this test image is spectacular, with no hint to the eye of any smear or blurring. A high signal-to-noise ratio reveals fine details even in the shadows.
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PIA08014_modest.jpgThe "First Frame" from MRO (detail mgnf)82 visiteThe scene covers an area 49,8 Km (about 30,9 mi) wide and 23,6 Km (about 11,7 mi) high, of landscape typical of Mars' mid-latitude Southern Highlands. The location is 34° South Latitude, 305° East Longitude. An old, muted crater lies at the middle of the scene, with sets of channels to the left and right. Superimposed on parts of this terrain is a much younger, layered mantle of debris. The debris mantle is smooth in places but rough in other areas where it may have partially sublimated. This suggests that the debris mantle is (or was) rich in volatiles such as ices of water, CO2 or both. Also superimposed on the landscape are many small sharp-rimmed impact craters and wind-blown dunes. This image illustrates processes that may have involved water both on ancient Mars (channels and eroded craters) and much more recently in Mars' history (volatile-rich debris mantle). The radiometric and geometric processing of this image is very preliminary. In particular there are mismatches visible at full resolution along the seams between the 10 side-by-side images from separate CCDs (charge-coupled devices, which are electronic optical sensors).
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PIA10139-FansField~0.jpgFans Field (MULTISPECTRUM; credits: Lunexit)53 visiteAt the very beginning of Spring in the Southern Hemisphere on Mars the ground is covered with a seasonal layer of CO2 ice.
In this image there are 2 lanes of undisturbed ice bordered by 2 lanes peppered with Fans of dark dust.
When we zoom in to the image, we see that the Fans are seen to be pointed in the same direction, dust carried along by the prevailing wind. The Fans seem to emanate from spider-like features.
Image Data: the image is centered at -86,4° Latitude and 99,1° East Long.
The range to the target site was 276,1 Km (about 172,6 miles). At this distance the image scale is 55,2 cm/pixel (with 2x2 binning) so objects ~166 cm across are resolved.
The image was taken at 16:27 MLT (middle afternoon), with the Sun just 2° above the Local Horizon. MareKromium
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PIA10140-DarkFans~0.jpgBright Streaks and Dark Fans (MULTISPECTRUM; credits: Lunexit)53 visiteIn a Region of the South Pole known informally as "Ithaca", numerous Fans of dark frost form every Spring. HiRISE collected a time lapse series of these images, starting at Ls = 185 and culminating at Ls = 294. "Ls" is the way we measure time on Mars: at Ls = 180 the Sun passes the Equator on its way South; at Ls = 270 it reaches its maximum subsolar latitude and Summer begins.
We believe that the bright streaks are fine frost condensed from the gas exiting the vent. The conditions must be just right for the bright frost to condense. MareKromium
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PIA10141-AraneiformTerrain~0.jpgAraneiform and Lace Terrains (MULTISPECTRUM; credits: Lunexit)53 visiteThe South Polar Terrain on Mars contains landforms unlike any that we see on Earth, so much that a new vocabulary is required to describe them. The word "araneiform" means "spider-like".
There are radially organized channels on Mars that look spider-like, but we don't want to confuse anyone by talking about "spiders" when we really mean "channels", not "bugs."
This picture shows an example of "connected araneiform topography", such as terrain that is filled with spider-like channels whose arms branch and connect to each other. Gas flows through these channels until it encounters a vent, where is escapes out to the atmosphere, carrying dust along with it. The dark dust is blown around by the prevailing wind.
This image also shows a different Region where the channels are not radially organized. In this Region they form a dense tangled network of tortuous strands. We refer to this as "lace". MareKromium
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PIA10142-SeasonalDryIce~0.jpgTranslucent Seasonal Ice (MULTISPECTRUM; credits: Lunexit)53 visiteIn a Region near the South Pole of Mars, translucent Carbon Dioxide ice covers the ground seasonally. For the first time we can "see" the translucent ice by the affect it has on the appearance of the surface below.
Dark fans of dust from the surface drape over the top of the seasonal ice.
The surface would be the same color as the dust except that the seasonal ice affecting its appearance. Bright bluish streaks are frost that has re-crystallized from the atmosphere.
Sunlight can penetrate through the seasonal layer of translucent ice to warm the ground below. That causes the seasonal ice layer to sublime (evaporate) from the bottom rather than the top. MareKromium
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PIA10144-DarkFans~0.jpgBright Streaks and Dark Fans (MULTISPECTRUM; credits: Lunexit)53 visiteThe South Polar Region of Mars is covered every year by a layer of Carbon Dioxide (CO2) ice. In a Region called the "cryptic terrain", the ice is translucent and sunlight can penetrate through the ice to warm the surface below.
The ice layer sublimates (evaporates) from the bottom. The Dark Fans of dust seen in this image come from the surface below the layer of ice, carried to the top by gas venting from below. The translucent ice is "visible" by virtue of the effect it has on the tone of the surface below, which would otherwise have the same color and reflectivity as the Fans.
Bright streaks in this image are fresh frost. The CRISM team has identified the composition of these streaks to be Carbon Dioxide.
Nota Lunexit: questa è la surface feature che ha "stimolato" l'immaginazione di Joseph Skipper e Richard Hoagland. Secondo costoro, le "dark features" sarebbero alberi simili ai "pioppi" terrestri... Ogni ulteriore commento ci sembra davvero inutile.MareKromium
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PIA10145-CrypticTerrain~0.jpgCryptic Terrain (MULTISPECTRUM; credits: Lunexit)72 visiteThere is an enigmatic Region near the South Pole of Mars known as the "cryptic" terrain. It stays cold in the Spring, even as its albedo darkens and the Sun rises in the sky.
This Region is covered by a layer of translucent seasonal CO2 ice that warms and evaporates from below. As CO2 gas escapes from below the slab of seasonal ice it scours dust from the surface. The gas vents to the surface, where the dust is carried downwind by the prevailing wind.
The channels carved by the escaping gas are often radially organized and are known informally as "spiders". MareKromium
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PIA10146-Fans~0.jpgTranslucent Seasonal Ice (MULTISPECTRUM; credits: Lunexit)96 visiteEvery year seasonal CO2 ice, known to us as "dry ice", covers the Poles of Mars. In the South Polar Region this ice is translucent, allowing sunlight to pass through and warm the surface below. The ice then sublimes (evaporates) from the bottom of the ice layer, and carves channels in the surface.
The channels take on many forms. In the image shown here the gas from the dry ice has etched wide shallow channels. This Region is relatively flat, which may be the reason these channels have a different morphology than the "spiders" seen in more hummocky terrain. MareKromium
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PIA10147-Starburst_Channels-PCF-LXTT.jpgThe "Arthur Clarke Trees" (Enhanced Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)208 visitenessun commentoMareKromium
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PIA10148-LizardSkinTerrain~0.jpgLizard-Skin Surface Texture (natural colors; elab. Lunexit)54 visite The South Polar Region of Mars is covered seasonally with translucent CO2 ice.
In the Spring, gas subliming (evaporating) from the underside of the seasonal layer of ice bursts through weak spots, carrying dust from below with it, to form numerous Dust Fans aligned in the direction of the prevailing wind.
The dust gets trapped in the shallow grooves on the surface, helping to define the small-scale structure of the surface. The surface texture is reminiscent of lizard skin.MareKromium
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